JP2023124977A - Fixing device - Google Patents

Abstract

To provide a fixing device that prevents lubricant from reaching an outer surface of a fixing belt to prevent a reduction in image quality.SOLUTION: A fixing device comprises a rotatable fixing belt, a heating roller, a steering roller, a pressure rotating body, and a slide member, and the pressure rotating body forms a nip part with the fixing belt. The fixing device fixes a toner image to a recording material at the nip part. Lubricant is applied to an inner peripheral surface of the fixing device. The slide member has a plurality of projections that slide with the fixing belt. In a state in which the nip part is formed, both ends in a width direction of the fixing belt are located outside an area where the projections are formed.SELECTED DRAWING: Figure 6

Description

The present invention relates to a fixing device that fixes a toner image onto a recording material.

The image forming apparatus includes a fixing device that fixes an unfixed toner image on the recording material to the recording material.

The fixing device includes a heating roller having a heat source for heating an unfixed toner image, an endless rotatable fixing belt to which heat is applied from the heating roller, and a pressure roller that presses the fixing belt. is known (Patent Document 1). The heating roller is disposed on the inner peripheral surface of the fixing belt and suspends the fixing belt. The pressure roller is located on the outer peripheral surface of the fixing belt, and forms a nip portion with the fixing belt by pressurizing the pad member via the fixing belt. A recording material carrying an unfixed toner image is conveyed to this nip portion, and when it is nipped and conveyed by the nip portion, heat and pressure are applied to fix the toner on the recording material.

It is known that in the fixing device using the fixing belt described above, steering control is performed to adjust the position of the fixing belt in the width direction. By performing steering control, scratches caused by edges of the recording material are suppressed. Further, the fixing belt is prevented from coming off the member that suspends the fixing belt.

2. Description of the Related Art As the printing speed of image forming apparatuses increases, fixing devices with a wider fixing nip width in the recording material conveyance direction have been proposed. By widening the fixing nip width, it is advantageous to cope with higher speeds. On the other hand, increasing the nip width increases the sliding resistance between the pad member and the fixing belt. Therefore, a configuration is known in which the sliding resistance is reduced by applying a lubricant to the inner circumferential surface of the fixing belt and using a sliding member to increase the slidability between the fixing belt and the pad member.

JP2003-195671

The fixing belt was shorter than the sliding member in the width direction. Therefore, the oil leaking from the inner circumferential surface of the belt ends up adhering to the sliding member on the outside of the fixing belt. Then, as the steering control is performed, there is a possibility that the oil adhering to the sliding member may adhere to the outer circumferential surface of the fixing belt. Thereafter, the oil adhering to the outer peripheral surface of the fixing belt is transferred to the recording material, resulting in a reduction in image quality.

Therefore, it is an object of the fixing device according to the present invention to suppress the deterioration in image quality caused by oil being transferred to the recording material.

In view of the above problems, the fixing device according to the present invention includes a rotatable endless fixing belt, a heating roller that contacts the inner peripheral surface of the fixing belt and applies heat to the fixing belt, and together with the heating roller, the fixing device. a steering roller that contacts an inner circumferential surface of the belt and changes the position of the fixing belt in the width direction of the fixing belt; and a pressure rotating body that presses the fixing belt and forms a nip portion together with the fixing belt. , a recording material carrying unfixed toner is conveyed between the nip portion and a sliding member that is in contact with the inner circumferential surface of the fixing belt and is capable of sliding on the inner circumferential surface of the fixing belt; In a fixing device that fixes a toner image on a recording material, a lubricant is applied to an inner circumferential surface of the fixing belt, and the sliding member has a plurality of protrusions that slide on the fixing belt. In the state where the nip portion is formed, both ends of the fixing belt in the width direction are located outside the area where the projection portion is formed.

According to the fixing device of the present invention, it is possible to reduce the amount of oil adhering to the outer peripheral surface of the fixing belt, thereby suppressing deterioration in image quality.

FIG. 1 is a schematic cross-sectional view of an image forming apparatus in this embodiment. FIG. 3 is a schematic cross-sectional view of a fixing device in this embodiment. FIG. 2 is a perspective view of a fixing device in this embodiment. FIG. 3 is a diagram of the fixing device according to the present embodiment viewed from the conveyance direction. It is a schematic diagram of the sliding member in this embodiment. It is a schematic diagram of the nip part containing the sliding member in this embodiment. It is a schematic diagram of the nip part containing the sliding member in this embodiment. It is a schematic diagram of the nip part containing the sliding member in a modification.

Hereinafter, an embodiment of an image forming apparatus according to the present embodiment will be described based on the drawings. Note that although an example in which the present invention is applied to an electrophotographic full-color image forming apparatus having a plurality of photosensitive drums will be described below, the present invention is not limited to this, and can also be applied to monochrome image forming apparatuses. can.

<Image forming device>
A schematic configuration of an image forming apparatus 100 of this embodiment will be described using FIG. 1.

FIG. 1 is a diagram showing a full-color image forming apparatus according to this embodiment. The image forming apparatus 100 forms four types of images along the moving direction of the intermediate transfer belt 115: a yellow image forming section 120a, a magenta image forming section 120b, a cyan image forming section 120c, and a black image forming section 120d. 110 is arranged. First, the process of forming a toner image on the intermediate transfer belt 115 will be described using the yellow image forming section 120a as an example.

In FIG. 1, a charger 112 uniformly charges the surface of a rotationally driven photosensitive drum 111 (charging). Thereafter, the exposure device 113 irradiates the surface of the photosensitive drum 111 with a laser according to the input image data, and an electrostatic latent image is formed on the surface of the photosensitive drum 111 (exposure). Thereafter, a yellow toner image is formed on the photosensitive drum 111 by the developing device 114. The primary transfer roller 117 applies a voltage having a polarity opposite to the potential polarity of the yellow toner image to the intermediate transfer belt 115. As a result, the yellow toner on the photosensitive drum 111 is transferred to the intermediate transfer belt 115 (primary transfer). Note that the yellow toner remaining on the surface of the photosensitive drum 111 without being transferred is scraped off by a toner cleaner and removed from the surface of the photosensitive drum 111. This series of processes is similarly performed in the magenta image forming section 120b, the cyan image forming section 120c, and the black image forming section 120d. As a result, a full-color toner image is formed on the intermediate transfer belt.

The toner image on the intermediate transfer belt 115 is conveyed to a secondary transfer portion N2 formed by a secondary transfer roller 116. The recording materials P are taken out one by one from the recording material cassette 103 and fed to the secondary transfer section N2 in accordance with the timing at which the toner images are conveyed. Then, the toner image on the intermediate transfer belt 115 is transferred onto the recording material P (secondary transfer).

The recording material P onto which the toner image has been transferred is conveyed to the fixing device 200, where it is fixed by heat and pressure (fixing). The recording material P with the toner image fixed thereon is discharged to a paper discharge tray.

The image forming apparatus 100 can also perform monochrome image formation. When forming a monochrome image, only the black image forming section 120d among the plurality of image forming sections 110 is driven.

When forming images on both sides of the recording material P, when the toner transfer and fixing on the first side (first side) of the image formation is completed, the recording material P is transported by a flapper 132 provided inside the image forming apparatus after fixing. route 134. Then, the recording material P is conveyed to the reversing section 136. When the reversal sensor 135 detects the rear end of the recording material P, the flapper 133 switches the conveyance direction of the recording material P to the reversal path 137. The image forming apparatus 100 conveys the reversed recording material P to the image forming section 110 and then to the fixing device 200 again via the reverse path 137. The recording material P that has been printed on both sides is guided to a discharge path 139 by a flapper 132 and discharged to the outside.

This process starting from charging until the recording material P on which the toner image is fixed is discharged to a paper discharge tray is referred to as an image forming process (print job). Further, the period during which image formation is being performed is assumed to be during image formation processing (during print job).

The operation unit 180 includes a display screen and selection keys. The operation unit 180 displays the status of the image forming apparatus 100 on a display screen and accepts operation instructions from an operator (user) using selection keys.

The control board 150 includes a control section 151 and a memory 152, and controls each unit within the image forming apparatus 100 described above. The control unit 151 sends output signals to each electrical component in order to operate the electrical component at a desired timing and with a necessary amount of control, based on detection signals input from each sensor and information stored in the memory 152. Output to. Therefore, it is this control section 151 that actually controls the electrical components. The memory 152 stores information data necessary for controlling each unit section, and the control section 151 reads and writes the information data stored in the memory 152.

<Fixing device>
Next, details of the configuration of the fixing device in this embodiment will be described using FIGS. 2 and 3. FIG. 2 is a sectional view of a fixing device according to an embodiment of the present invention, and FIG. 3 is a partial perspective view of the fixing device 200. FIG. 2 shows a schematic diagram of the overall configuration of a belt heating type fixing device 200 according to the present embodiment. In FIG. 2, the recording material P is conveyed from right to left on the paper surface. The fixing device 200 includes a heating unit 210 having a heat source, and a pressure rotating body (hereinafter referred to as a pressure roller) 202 that forms a nip portion N together with the heating unit 210. The heating unit 210 includes a fixing belt (hereinafter referred to as a belt) 201 as an endless rotatable heating rotating body, a pad member (hereinafter referred to as a pad) 203 as a fixing member, a heating roller 204, and a steering roller 205. have

The belt 201 has thermal conductivity, heat resistance, etc., and has a thin cylindrical shape. This embodiment has a three-layer structure including a base layer, an elastic layer around the outer periphery of the base layer, and a releasable layer around the outer periphery of the base layer. The base layer has a thickness of 60 μm and is made of polyimide resin (PI), the elastic layer has a thickness of 300 μm and is made of silicone rubber, and the release layer has a thickness of 30 μm and is made of PFA (tetrafluoroethylene perfluorocarbon resin) as a fluororesin. alkoxyethylene copolymer resin) is used. The belt 201 is stretched by a pad 203, a heating roller 204, and a steering roller 205.

The pad 203 is a member that comes into pressure contact with the pressure roller 202 via the belt 201 to form a nip portion N of a predetermined width in the recording material conveyance direction. The belt 201 has a substantially rectangular cross section and is a long member along the width direction of the belt 201 . The material of the pad 203 needs to be heat resistant, and is made of LCP (liquid crystal polymer) resin.

A sliding member 207 and silicone oil S (hereinafter referred to as oil S) as a lubricant are interposed between the pad 203 and the belt 201, so that the belt 201 slides smoothly on the pad 203. ing.

The oil supply roller 208 is formed by impregnating silicone oil into a roll-shaped member wound with a nonwoven fabric having a thickness of 100 μm. The oil supply roller 208 is brought into contact with the inner surface of the belt 201 at 3.0 N by a pressure spring 209, and is supported by the frame of the heating unit 210 so as to be rotatable.

The oil S applied as a lubricant between the pad 203 and the belt 201 deteriorates as the fixing device 200 operates and decreases due to leakage to the outside. If the oil S between the pad 203 and the belt 201 cannot be held, the sliding resistance between the pad 203 and the belt 201 increases, which may cause problems such as poor rotation of the belt 201. The oil supply roller 208 comes into contact with the belt 201, thereby making it possible to supply the oil S to the inner peripheral surface of the belt 201. This makes it possible to maintain the oil S present between the belt 201 and the pad 203 (sliding member 207) for a longer period of time, and to maintain stable operation of the fixing device 200. Although the fixing device 200 in this embodiment has an oil supply roller 208, the inner peripheral surface of the belt 201 may be coated with oil S during the manufacturing process of the fixing device 200. . In other words, the fixing device 200 may not include the oil supply roller 208.

A stay 206 is arranged inside the belt 201. The stay 206 is arranged inside the pad 203 on the opposite side to the sliding member 207 side. The stay 206 is a reinforcing member that backs up the pad 203 and is long in the width direction of the belt 201 and has rigidity. The material used is drawn SUS304 material with a wall thickness of 3 mm, and the cross section is formed into a hollow "square" shape to ensure strength. The stay 206 provides strength to the pad 203 and secures the pressing force at the nip portion N when the pad 203 is pressed against the pressure roller 202. Note that the material of the stay 206 is not limited to stainless steel as long as its strength can be ensured.

The heating roller 204 is a stainless steel pipe with a thickness of 1 mm, and a halogen heater (not shown) is disposed inside thereof, and can generate heat up to a predetermined temperature. The belt 201 is heated by a heating roller 204 and controlled to a predetermined target temperature depending on the paper type based on temperature detection by a thermistor. Further, the heating roller 204 may be configured to be rotationally driven. By rotationally driving the heating roller 204, it is possible to increase the tension of the belt 201 from the nip portion N to the heating roller 204 in the belt rotation direction. By doing so, the curvature of the exit of the nip portion N can be increased in the belt rotation direction, and the separation performance of the recording material P can be improved.

Steering roller 205 suspends belt 201 and is supported by steer frame 213 . As the steer frame 213 rotates about the rotation shaft 212 with respect to the frame of the heating unit 210, the steering roller 205 changes its alignment with respect to other suspension members. Thereby, a difference in tension is generated between the front and rear sides of the belt 201. Then, as shown in FIG. 4, the position of the belt 201 is controlled by moving the belt 201 in the U direction in the width direction of the belt 201. Note that this steering roller 205 is biased by a spring 211 supported by a steer frame 213, and also has the role of a tension roller that applies a predetermined tension to the belt 201.

Furthermore, the steering roller 205 also plays a role in suppressing uneven gloss caused by the edges of the recording material P. In this embodiment, a force of approximately 2000 N is applied to the belt 201 at the nip portion N. When fixing unfixed toner to the recording material, the portion of the belt 201 that contacts the edge of the recording material P is subjected to greater stress than the portion that does not come into contact with the edge. The area where the edge of the recording material has repeatedly passed has a concave shape compared to the non-contact area of the edge. The dents caused on the surface of the belt 201 by the edges of the recording material are called paper edge scratches.

When fixing unfixed toner to a recording material, the fixing device 200 applies pressure and heat to the recording material. At this time, the surface condition of the belt 201 is reflected in the gloss of the image surface after fixing. If unevenness exists on the surface of the belt 201, the unevenness will be reflected in the gloss of the image surface, resulting in uneven gloss (glossy unevenness) on the image surface. Therefore, if unfixed toner is fixed to a recording material with paper edges scratched on the surface of the belt 201, uneven gloss that looks like a straight line will occur on the image surface. Therefore, in this embodiment, in order to suppress paper edge scratches on the surface of the belt 201, the belt 201 is reciprocated in the width direction.

The fixing device 200 in this embodiment includes a position detection section (not shown) that detects the position of the belt 201 in the width direction. An arm is provided at an end of the belt 201 and abuts against the belt 201 from the outside to the inside in the width direction. By detecting the position of this arm with a sensor such as a photointerrupter, the position of the belt 201 in the width direction can be determined. In order to accurately detect the position of the belt 201 in the width direction, the direction in which the arm applies force to the belt 201 is from the outside to the inside of the belt 201 in the width direction. Further, in order to apply force in this direction, the rotation axis of the arm is in a direction perpendicular to the width direction. Therefore, the arm that detects the position of the belt in the width direction rotates in the width direction about the aforementioned rotation axis. By detecting the position of the belt 201 in the width direction, it is possible to prevent the belt 201 from coming off the members (the pad 203, the heating roller 204, and the steering roller 205) that suspend the belt 201. Further, the belt 201 can be actively moved in the width direction to prevent edge scratches.

The pressure roller 202 is a roller having an elastic layer formed around the outer periphery of the shaft and a release layer formed around the outer periphery. The shaft is made of stainless steel, the elastic layer is 5 mm thick and made of conductive silicone rubber, and the release layer is 50 μm thick and made of PFA as a fluororesin. The pressure roller 202 is axially supported by the fixing frame 380 of the fixing device 200, has a gear fixed to one end thereof, is connected to a drive source M via the gear, and is rotationally driven. The belt 201 is driven to rotate in the R direction by being held between the rotating pressure roller 202 and the pad 203.

<Contact/separation mechanism>
The contact and separation mechanism of the pressure roller 202 will be explained. The pressure roller 202 can be moved to a position where it contacts or separates from the belt 201 by a contact/separation mechanism. The contact/separation mechanism includes a pressure frame 202b and a drive motor. The pressure frame 202b supports the pressure roller 202. The pressure frame 202b is driven by a drive motor and rotates about the pressure rotation shaft 202a as a rotation axis. When the drive motor rotates the pressure frame 202b clockwise on the paper with the pressure rotation shaft 202a as the rotation axis, the pressure roller 202 moves in the direction of arrow P. As a result, the pressure roller 202 is brought into contact with the pad 203 across the belt 201 in a direction perpendicular to the conveying direction of the recording material, that is, in the pressing direction (contact state). As a result, a fixing nip portion N is formed. When the pressure frame 202b is rotated counterclockwise on the paper with the pressure rotation shaft 202a as the rotation axis, the pressure roller 202 is separated from the belt 201 (separated state).

In this way, the pad 203, the heating roller 204, and the steering roller 205 are arranged on the inner peripheral surface of the belt 201, and the belt 201 is suspended. The belt 201 is held between a pressure roller 202 and a pad 203, and rotates as the pressure roller 202 rotates. The belt 201 stores heat from the heating roller 204. When the recording material P carrying the unfixed toner image is conveyed while being held between the pressure roller 202 and the belt 201 at the nip portion N, heat and pressure necessary for fixing are applied to the recording material P. Then, the toner image is fixed on the recording material P.

<Sliding member>
The pad 203 is pressed by the pressure roller 202 via the belt 201, thereby forming a fixing nip portion N. The pad 203 is made of LCP (liquid crystal polymer) resin. A sliding member 207 is interposed between the pad 203 and the belt 201.

In the fixing device F of this embodiment, since the pressure applied to the fixing nip N is 1600 N and the nip width is 24.5 mm, the sliding resistance with the pad 203 on which the belt 201 is stretched is large. In order to reduce sliding resistance, a sliding member 207 that can slide on the belt 201 is provided on the belt 201 side of the pad 203. Details are described below.

The detailed configuration of the sliding member 207 is shown in FIG. FIG. 5A is a cross-sectional view of the sliding member 207 in a case where the left-right direction on the paper is the conveying direction (X direction) and the up-down direction is the pressing direction (Z direction). FIG. 5b) is a diagram of the sliding member 207 viewed from the pressure roller 202 side, with the left-right direction on the paper being the width direction (Y direction) and the up and down direction being the conveyance direction (X direction). As shown in FIG. 3A, the sliding member 207 of this embodiment includes a base portion 207a, an embossed portion 207b, which is a projection, and a sliding layer 207c. The base material portion 207a only needs to have sufficient heat resistance and strength. Desirable materials include SUS, copper, aluminum, and engineering plastics (PI, PEEK, LCP, etc.). In this embodiment, the sliding member 207 is arranged at equal intervals in the width direction so that the distance d between the embossments (distance between the protrusions) is 1.4 mm. By providing the embossed portion 207b, the contact area with the belt 201 is reduced, thereby reducing sliding resistance. In this embodiment, the base portion 207a and the embossed portion 207b are made of SUS, which is a metal. It is not limited to SUS, but preferably a metal with excellent heat resistance and durability.

The sliding layer 207c is preferably provided with a material (fluorine coat, PTFE, PFA, etc.) in order to achieve low friction. In this example, PTFE (polytetrafluoroethylene) was coated with a thickness of 20 μm. As mentioned above, the frictional force between the inner peripheral surface of the belt 201 and the sliding member 207 is very large, so by further applying lubricant, the belt 201 can slide smoothly on the sliding member 207. Become. Silicone oil was used as the above lubricant.

The sliding member 207 of this embodiment is configured to cover the pad 203 regardless of whether it is inside or outside the nip portion N. Although not shown hereafter, it does not matter if a part of the fixing nip portion N is covered with the sliding member 207. That is, a configuration in which the sliding member 207 is disposed only in the nip portion N may be used.

In this embodiment, the embossed portion 207b of the sliding member is provided over the entire area of the sliding member 207. Although not shown hereafter, it does not matter if a part of the fixing nip N is covered with the embossed part 207b of the sliding member. That is, a configuration in which the embossed portion 207b of the sliding member is disposed only in the nip portion N may be used. The embossed portion 207b provided in the nip portion N is in contact with the belt 201 via a sliding layer 207c.

In this embodiment, a configuration in which the sliding member 207 is fixed to the stay 206 is adopted. (Not shown) Although not shown here, the sliding member 207 and the pad 203 may be integrated. Further, a portion of the sliding member 207 may be fixed to the stay 206 or the pad 203. For example, both ends of the sliding member 207 in the Y direction (width direction) may be fixed to the pad 203 with screws or the like.

In this embodiment, the pressing force applied to the fixing nip N is 1600 N, the length of the fixing nip N in the transport direction is 24.5 mm, and the length in the width direction is 326 mm.

<Deterioration of image quality due to lubricant>
A lubricant, oil S, is used in the fixing device 200 using the belt 201 as in this embodiment. Oil S is applied to the inner peripheral surface of the belt 201. In the nip portion N, since a pressing force is generated by the pad 203 and the pressure roller 202, the oil S applied to the inner peripheral surface of the belt 201 is pushed out from the inner peripheral surface of the belt 201. acts. If the belt 201 is shorter than the sliding member 207 and the pad 203 in the width direction, the extruded oil S will travel through the sliding member 207 and the pad 203 and adhere to the outer peripheral surface of the belt 201. There is a possibility.

Further, in this embodiment, the belt 201 is reciprocated in the width direction using a steering roller 205. Here, if there is oil S exposed in the outer region of the belt 201, the oil S will noticeably adhere to the outer surface of the belt 201. Since the belt 201 rotates in the R direction in FIG. 2, the oil S attached to the outer surface of the belt 201 ends up reaching the nip portion N. Then, when the oil S adheres to the recording material P conveyed to the nip portion N, the area to which the oil S adheres becomes a defective image. Therefore, it is necessary to prevent the oil S from adhering to the area of the belt 201 that contacts the recording material S.

The oil S travels from the inner circumferential surface of the belt 201 to the unevenness provided on the sliding member 207 before reaching the outer surface of the belt 201 . Therefore, in the fixing device 200 in this embodiment, the length of the belt 201 is made longer than the area where the embossed portion 207 is provided in the width direction. The details are described below.

<Relationship between the length of the belt and the sliding member>
The relationship in the width direction will be explained using FIG. 6. FIG. 6 is a diagram showing one end of the fixing device 200 including the belt 201, the pad 203, and the sliding member 207. The left and right direction on the paper of FIG. 6 is defined as the width direction. Since the other end has the same relationship, a description thereof will be omitted.

The sliding member 207 has a region where the embossed portion 207b is provided and a non-installed region 207e where the embossed portion 207b is not provided outside the region in the width direction where the embossed portion 207b is provided.

As shown in FIG. 6, the belt 201 is longer in the width direction than the area of the sliding member 207 where the embossed portion 207b is installed.

The oil S applied between the inner circumferential surface of the belt 201 and the embossed portion 207b leaks outside the area where the embossed portion 207b is installed. However, since the belt 201 is long in the width direction, the oil S leaking outside the area where the embossed portion 207b is installed is difficult to reach the outer surface of the belt 201. Therefore, the oil S is easily maintained on the inner circumferential surface of the belt 201, and it is possible to suppress the oil S from adhering to the outer surface of the belt 201.

Further, the belt 201 and the pad 203 are in contact at the exit of the nip portion N. Therefore, if the oil S adheres to the pad 203, there is a possibility that the oil S may be transmitted through the pad 203 and adhere to the outer surface of the belt 201. For this reason, as shown in FIG. 6, in this embodiment, the belt 201 is longer than the pad 203 in the width direction.

In this embodiment, a steering roller 205 is used. The position of the end portion 207g of the belt 201 in the width direction is changed by the steering roller 205. However, as shown in FIG. 7, even when the end portion 207g of the belt 201 is changed by the steering roller 205, the end portion 207g of the belt 201 is located outside the embossed portion 207b in the width direction. Thereby, even in the fixing device 200 having the steering roller 205, it is possible to suppress the oil S from adhering to the outer surface of the belt 201. In this form, oil S leaking from the embossed portion 207b is deposited in the non-installation area 207e. However, the oil S deposited in the non-installation area 207e is pulled back inside the belt 201 in the width direction by surface tension. As a result, since the oil S is resupplied from the non-installation area 207e, it is possible to suppress the oil S from adhering to the outer surface of the belt 201.

The steering roller 205 changes the position of the end portion 201g of the belt 201 in the width direction. However, as shown in FIG. 8 as a modified example, even when the end 201g of the belt 201 is changed by steering control, the end 201g of the belt 201 is closer to the end 203g of the pad than the end 207g of the sliding member 207. It is also possible to have a configuration in which the elements are located outside. Thereby, it is possible to suppress the oil S from being transmitted through the pad 203 and the sliding member 207 and adhering to the outer surface of the belt 201.

Note that in this embodiment, the sliding member 207 is fixed to the stay 206 with screws or the like. Regions into which the screws are inserted are provided at both ends of the sliding member 207 in the width direction. Therefore, the length including the sliding member 207 and the region into which the screw is inserted is longer than the length of the belt 201 in the width direction. However, the region into which the screw is inserted is not limited to both ends in the width direction, but may be both ends in the conveyance direction. In other words, the area into which the screw is inserted is not included in the non-installation area 207e.

100 Image forming apparatus 200 Fixing device 201 Fixing belt 202 Pressure roller 203 Pad 204 Heating rotating body 205 Steering roller 206 Stay 207 Sliding member

Claims (5)

a rotatable endless fixing belt; a heating roller that contacts an inner peripheral surface of the fixing belt and applies heat to the fixing belt;
a steering roller that contacts the inner peripheral surface of the fixing belt together with the heating roller and changes the position of the fixing belt in the width direction of the fixing belt;
a pressure rotating body that presses the fixing belt and forms a nip portion with the fixing belt;
a sliding member that comes into contact with the inner circumferential surface of the fixing belt and is capable of sliding on the inner circumferential surface of the fixing belt;
A fixing device that causes the nip portion to nip and convey a recording material carrying unfixed toner, and fixes the unfixed toner image to the recording material,
A lubricant is applied to the inner peripheral surface of the fixing belt,
The sliding member has a plurality of protrusions that slide on the fixing belt,
A fixing device characterized in that, in a state where the nip portion is formed, both ends of the fixing belt in the width direction are located outside an area where the protrusion portion is formed. The fixing device according to claim 1, further comprising a pad member that holds the sliding member and forms a nip portion by sandwiching the fixing belt together with the pressure rotating body. The fixing device according to claim 2, wherein the length of the pad member in the width direction is shorter than the length of the fixing belt in the width direction in a state where the nip portion is formed. 4 . The fixing belt according to claim 1 , wherein both ends of the fixing belt are located outside of the pressure rotating body in the width direction when the nip portion is formed. 4 . fixing device. 5. In the width direction, the sliding member has a non-installation area, which is an area where the protrusion is not provided, outside the area where the protrusion is formed. The fixing device according to item (1).

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